Let's do some math ..  Rounding examples of 7 random hypothetical purchases:
Case	Tag   Price	Sales   Tax %	Raw Total   Incl. Sales Tax	Rounded   to Penny	Rounded   to Nickel	Rounded   to Dime
Purchase #1	$170.69	12.337%	$191.748	$191.75	$191.75	$191.70
Purchase #2	$95.53	6.159%	$101.4137	$101.41	$101.40	$101.40
Purchase #3	$156.40	5.108%	$164.3889	$164.39	$164.40	$164.40
Purchase #4	$199.41	5.373%	$210.1243	$210.12	$210.10	$210.10
Purchase #5	$88.54	8.155%	$95.7604	$95.76	$95.75	$95.80
Purchase #6	$171.35	6.384%	$182.289	$182.29	$182.30	$182.30
Purchase #7	$145.76	3.505%	$150.8689	$150.87	$150.85	$150.90
7 purchase totals =	$1,027.68		$1,096.5932	$1,096.59	$1,096.55	$1,096.60